What resource / topic should I study to get more knowledge in business logic development?

I'm interested in learning different ways available to develop the logic for a business application development.

For example. consider the design of an software for payroll system for a company which has multiple branches. How do I represent these branches logically in my application, such that an manager logging into the payroll system could belong to one or more branch but can keep only one branch active at a time for any type of payroll processing or reports? Can you suggest more than one ways the logic can be defined for this app?

I'm looking for material to read/study regarding this side of logic. I'm not familiar as to what it is called as System Design / Software Architecture / Design patterns? I couldn't find much details on web via search, maybe cause I didn't know what exactly to look for.

So far I've only developed CRUD apps that didn't have much logic applicable to it. Looking to get into more complex applications with learning techniques and guidelines to make them scalable, modular and efficient. Any help on this topic is appreciated. Thanks.

Did pretty detailed search on internet for examples of such business logic, Not sure where if i searched wrong or something else, couldn't find the answers i was looking for.